Electrical heating cable with indicator light and manual test device

ABSTRACT

An elongated flexible electrical resistance heating cable adapted to be wrapped about water pipes and for other similar uses. A cold lead extends to the cable and a thermostat is interposed between the cold lead and the cable with a translucent and flexible envelope thereabout. A small indicator light within a second translucent envelope is connected in parallel with the heating cable and operates to reflect visually operation of the thermostat. A test device in the first envelope comprises a small spring metal conductor connected at one end with one thermostat terminal and having an opposite end movable toward and away from a second thermostat terminal. Manual deflection of the envelope against the conductor urges the same into contact with the terminal whereby to close the circuit for testing of the heating cable and release of manual pressure opens the circuit.

United States Patent [191 Daley I NOV. 26, 1974 ELECTRICAL HEATING CABLEWITH INDICATOR LIGHT AND MANUAL TEST DEVICE [75] Inventor: WilliamCarmen Daley, West Hartford, Conn.

[73] Assignee: Smith-Gates Corporation,

Farmington, Conn.

[22] Filed:

Nov. 29, 1973 21 Appl. No.: 420,263

52 user 219/528, 200/168 0,219/506, 219/535, 340/252 P 511 lnt.Cl.H05b3/36, H05b 3/56 [58] Field of Search 200/168 G; 219/528, 506,219/535, 549; 338/214; 340/252 R, 252 H,

[56] References Cited UNITED STATES PATENTS 2,696,607 12/1954 Witkin340/252 P 2,752,463. 6/1956 Staak 2,824,209 2/1958 Leipold 2,977,4563/1961 Stiebel 200/168 G 3,246,] 12 4/1966 200/168 G Adams et a13,305,668 2/1967 Smith 219/528 Primary Examiner-Volodymyr Y. MayewskyAttorney, Agent, or Firm-McCormick, Paulding and Huber [5 7] ABSTRACT Anelongated flexible electrical resistance heating cable adapted to bewrapped about water pipes and for other similar uses. A cold leadextends to the cable and a thermostat is interposed between the coldlead and the cable with a translucent and flexible envelope thereabout.A small indicator light within a second translucent envelope isconnected in parallel with the heating cable and operates to reflectvisually operation of the thermostat. A test device in the firstenvelope comprises a small spring metal conductor connected at one endwith one thermostat terminal and having an opposite end movable towardand away from a second thermostat terminal. Manual deflection of theenvelope against the conductor urges the same into contact with theterminal whereby to close the circuit for testing of the heating cableand release of manual pressure opens the circuit.

3 Claims, 3 Drawing Figures E E T ICAL HEATING CABLE WITH INDICATORLIGHT AN MANUAL TEST DEVICE BACKGROUND OF THE INVENTION Electricalheating cables of the resistance type have been .available heretoforeand have proven generally satisfactory. A convenient determination ofavailability of electricalpower, operability of the thermostat, andoperability of the resistance heating element has not, however, beenpossible with such heating cables, the cables often being disposed aboutwater pipes beneath house trailers andin other inaccessible locations.

- SUMMARY OF THE INVENTION It is the. general object of the presentinvention to provide an electrical resistance heating cable of the typementioned wherein provision is madefor the convenient visual indicationof the availability of electrical power supply, operability of athermostat, and wherein the operability of the resistance heatingelement may be readily ascertained.

BRIEF DESCRIPTION OF THE DRAWINGS DETAILED DESCRIPTION OF PREFERREDEMBODIMENTS Referring particularly to FIG. 1', an electrical resistanceheating cable is indicated generally at 10. The cable takes a tape-likeform in cross section with electrieal resistance heating element 12disposed therewithin and a flexible insulator 14 forming the sheath orouter portion thereof. Both the resistance heating element and theinsulator 14 are elongated and of indeterminant length extending from asubstantially translucent first envelope 16. The cable or tape mayobviously be woundconveniently in a spiral configuration about a waterpipe subject to freezing temperatures, embedded in seed beds, etc.

The translucent envelope 16, as best illustrated in FIG. 2, takes apillow configuration and is preferably heat sealed at end portions 18,about and in engage- .ment with the cable 10 and other elements. In FIG.3, and at the left-hand heat sealed area 18 in particular, a cold lead22, 24 is captured within the heat sealed area and extends therefrom toa conventional electrical plug 26, FIG. 1. The right-hand heat sealedarea 20 captures, in addition to the heating cable 10, first and "secondelectrical conductors 28, 30 which extend from clips 32, 34 to a secondsubstantially translucent envelope 36, best illustrated in FIG. 1.The'clips 32, 34 serve respectively to connect the conductors 28. and anassociated 'endportion of resistance element 12 with the cold lead 22and, to connect the conductor 30 and associated opposite end portion ofresistance element cent envelope 36 by means of the conductors 28, 30.

The thermostat 40 may be of a conventional construction and operates toenergize the heating element 7 12 below a predetermined temperaturewhereby to prevent-freezing of water pipes or to effect heating of theelement 12 for other end purposes. Preferably and as shown, thethermostat 40 has at least one exposed terminal and, left and right-handor first and second ex posed terminals are shown. The left-hand terminal42 is exposed for a purpose to be set forth hereinhelow and theaforementionedterminal 38 may also be-cxposed. The cold lead 24 isconnected with the left-hand terminal 42 by means of a suitable clip 44.

A test device incorporated in the heating cable assembly of the presentinvention is preferably manually operable and may comprise a springmetal conductor as illustrated at 46. The spring metal conductor 46 hasa right-hand portion 48 connected with the thermostat terminal 38 and aleft-hand portion 50 normally in spaced relationshipwith the thermostatterminal 42. An intermediate portion of the conductor 46 can be urgeddownwardly as illustrated by broken line 52 in FIG. 2 whereby to makecontactbetween the exposed terminal 42 and the portion'50 and tocomplete a circuit in parallel with the thermostat 40. As bestillustrated in FIG. 2, the intermediate portion of the spring metalconductor 46 is urged downwardly by manual depression of the translucentenvelope 16, illustrated by broken line 54.

From the foregoing, it will be apparent that the heating cable 10 may bewrapped about a water pipe, the plug 26 insertedin a suitable receptaclefor a supply of electrical power and the heating cable assembly willthereafter operate automatically to prevent freezing of water in apipe.The thermostat 40 will serve to energize the heating element 12 whenambient temperature drops below a predetermined level and to de-energizethe heating element when the ambient temperature exceeds such level.When the thermostat closes the circuit to energize the heating element,it also energizes the indicator or pilot lamp 42 and an observer canreadily determine visually the closed or operative condition of thethermostat. When the indicator or pilot light 42 is de-energized, theobserver is advised of the open or inoperative condition of thethermostat. The conductors or leads 28, 30 for the indicator or pilotlight 42 permit the orientation or positioning of the pilot lightexternally of insulation wrapping which may be placed about the heatingcable 10 on a water pipe. This of course permits a convenient visualinspection of the heating cable assembly for operability.

In testing operation of the heating cable assembly, the plug 26 may beintroduced to a convenient receptacle and the test device 46 maythereafter be manually depressed as indicated in FIG. 2 in the brokenline condition whereby to engage the portion 50 of the test device withthe exposed thennostat terminal 42. A parallel circuit is thus completedand the indicator light 42 will be energized to advise an observer as tothe availability of electrical power. Further, the resistance elel2 toaterminal 38 on a thermostat 40. Thus, the resistance heating element 12is connected in parallel with pilot or indicator means or lamp 42 withinthe translu- I claim:

I. An electrical heating cable assembly comprising:

a relatively thin, flexible heating cable including an elongatedelectrically conductive resistance heating element embedded in anelongated flexible insulator;

a thermostat electrically connected adjacent said heating element forcontrolling energization of the latter and having at least one exposedterminal;

visual indicating means comprising a small indicator light enclosedwithin a substantially translucent indicator envelope,

said visual indicating means being electrically connected to saidthermostat and heating element and operable on closing of saidthermostat for indicating energization of said heating element;

a test device electrically connected in parallel with said thermostatand operable manually to energize temporarily said heating element andindicating means,

and a substantially translucent envelope disposed about said thermostatand test device,

said test device comprising a movable metal conductor electricallyconnected at one end with one side of said thermostat and having itsother end disposed adjacent said exposed terminal,

said other end of said conductor being normally spaced from said exposedterminal to open a circuit parallel with said thermostat,

and said other end of said conductor being urged into contact with saidexposed terminal to complete said parallel circuit on the application ofmanual pressure to an intermediate portion of the conductor via saidtranslucent envelope.

2. An electrical heating cable as set forth in claim 1 wherein;

said translucent envelope has at least one flexible wall disposedadjacent but in spaced relationship with said test device,

said wall being flexible inwardly on the application of manually appliedpressure for operation of said test device as aforesaid.

3. An electrical heating cable as set forth in claim 1 wherein saidconductor is of a spring metal construction and flexibly movable.

1. An electrical heating cable assembly comprising: a relatively thin,flexible heating cable including an elongated electrically conductiveresistance heating element embedded in an elongated flexible insulator;a thermostat electrically connected adjacent said heating element forcontrolling energization of the latter and having at least one exposedterminal; visual indicating means comprising a small indicator lightenclosed within a substantially translucent indicator envelope, saidvisual indicating means being electrically connected to said thermostatand heating element and operable on closing of said thermostat forindicating energization of said heating element; a test deviceelectrically connected in parallel with said thermostat and operablemanually to energize temporarily said heating element and indicatingmeans, and a substantially translucent envelope disposed about saidthermostat and test device, said test device comprising a movable metalconductor electrically connected at one end with one side of saidthermostat and having its other end disposed adjacent said exposedterminal, said other end of said conductor being normally spaced fromsaid exposed terminal to open a circuit parallel with said thermostat,and said other end of said conductor being urged into contact with saidexposed terminal to complete said parallel circuit on the application ofmanual pressure to an intermediate portion of the conductor via saidtranslucent envelope.
 2. An electrical heating cable as set forth inclaim 1 wherein; said translucent envelope has at least one flexiblewall disposed adjacent but in spaced relationship with said test device,said wall being flexible inwardly on the application of manually appliedpressure for operation of said test device as aforesaid.
 3. Anelectrical heating cable as set forth in claim 1 wherein said conductoris of a spring metal construction and flexibly movable.